You'd think it would be a simple task, but smartphone wallpapers can be surprisingly difficult to pick out. Here's how to pick one you'll actually keep around for a while.

Wallpapers are a pretty personal thing, so we've included a few different options and approaches you can take. In the end, it's about what you find aesthetically pleasing, but that doesn't mean there aren't some best practices out there.

How to Change Your Smartphone's Wallpaper

First thing first, let's make sure you know how to change your phone's wallpaper. Good thing it's easy to do.

On Android:

Long press your home screen

Choose the Wallpaper option and pick your wallpaper of choice

Touch "Save" and you're all set

On iPhone:

Head into Settings > Wallpapers & Brightness

Tap "Choose Wallpaper"

Select a photo from your camera roll

Tap "Set" and choose either your lock screen or home screen.

Find the Right Resolution for Your Screen

When you're looking for wallpapers you need to know the resolution of your screen. That seems simple enough, but it's actually a little complicated. Depending on your device, your operating system, and what settings you have, you'll want to look for different sizes.

On Android, devices vary in resolution pretty wildly, but you can find your phone's resolution here. You'll then want to double the resolution's width because Android scrolls the wallpaper side-to-side when you swipe on your home screen. As for iPhones, you can check your resolution here. However, if you're using iOS 7, you probably have parallax enabled. This means you'll want to add about 200 pixels to your screen's resolution to get a wallpaper that looks right with the moving screen. If you're looking for some good parallax-specific wallpapers, Parallaxize is a good place to start.

Option 1: Search for Mobile and Desktop Wallpapers

Now that all those boring technical details are out of the way, it's time to hunt down wallpapers. The good news here is that you can search for phone or desktop wallpapers, and doing so will help expand your search.

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Generally speaking, there's a trick with smartphone wallpapers. For your home screen, you usually want something simple like a solid color or pattern. Since the icons on your screen tend to take up space, putting a picture back there is pretty useless in most cases. Of course, it's really up to you, but if you're struggling to find something that looks good, try finding an image that doesn't have a lot going on. Patterns, geometric shapes, and gradients often look really good on the home screen.

As for your lock screen, anything goes. Find an image you like that works around any lock screen widgets or clocks you have, and stick to it. For these, images that take up the whole screen tend to work best, but since the top half of your lock screen is usually pretty icon heavy, finding an image with the most interesting parts on the bottom tends to work best.

Option 2: Choose Functional Wallpapers

Your wallpaper doesn't have to just be good looking, it can be useful as well. While your home screen wallpaper can't be much more than a pretty thing to sit in the background, you can do a few clever things with your lock screen to make it more useful.

If you're really worried about losing your phone and you keep it locked with a passcode, you can set your lockscreen up with your name and phone number on it so people can easily get a hold of you. Or, if you're trying to remember something, like a school schedule, festival schedule, or just about any small piece of information, snap a picture of what you need to remember and you'll see it repeatedly throughout the day on your lock screen. Pretty? No, but at least it's useful.

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Option 3: Make Your Own

As we mentioned above, simple wallpapers usually work best for the home screen, but that doesn't have to mean boring. If you can't find any wallpapers you really like, you can make your own pretty easily.

For example, if you're a fan of gradients, Blur is an app for iOS that takes any photo from your camera roll and applies a heavy blur effect that makes a terrific background. Blur for Android does the same thing for Android devices. Likewise, an app like Grad for iPhone and Gradient Wallpapers for Android make simple gradients. If patterns are more your thing, Isometric is a great way to make backgrounds on iOS. Basically, if you're looking for a simple wallpaper they're easy enough to make on your own so you can pick the perfect colors.

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